/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.bumptech.glide.integration.volley;

import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;

import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * TODO: contribute cancel modifications to volley and remove this class.
 *
 * A Future that represents a Volley request.
 *
 * Used by providing as your response and error listeners. For example:
 * <pre>
 * RequestFuture&lt;JSONObject&gt; future = RequestFuture.newFuture();
 * MyRequest request = new MyRequest(URL, future, future);
 *
 * // If you want to be able to cancel the request:
 * future.setRequest(requestQueue.add(request));
 *
 * // Otherwise:
 * requestQueue.add(request);
 *
 * try {
 *   JSONObject response = future.get();
 *   // do something with response
 * } catch (InterruptedException e) {
 *   // handle the error
 * } catch (ExecutionException e) {
 *   // handle the error
 * }
 * </pre>
 *
 * @param <T> The type of parsed response this future expects.
 */
public class VolleyRequestFuture<T> implements Future<T>,
    Response.Listener<T>,
    Response.ErrorListener {
  private Request<?> mRequest;
  private boolean mResultReceived = false;
  private T mResult;
  private VolleyError mException;
  private boolean mIsCancelled = false;

  public static <E> VolleyRequestFuture<E> newFuture() {
    return new VolleyRequestFuture<E>();
  }

  public synchronized void setRequest(Request<?> request) {
    mRequest = request;
    if (mIsCancelled && mRequest != null) {
      mRequest.cancel();
    }
  }

  @Override
  public synchronized boolean cancel(boolean mayInterruptIfRunning) {
    if (isDone()) {
      return false;
    }
    mIsCancelled = true;
    if (mRequest != null) {
      mRequest.cancel();
    }
    notifyAll();

    return true;
  }

  @Override
  public T get() throws InterruptedException, ExecutionException {
    try {
      return doGet(null);
    } catch (TimeoutException e) {
      throw new AssertionError(e);
    }
  }

  @Override
  public T get(long timeout, TimeUnit unit)
      throws InterruptedException, ExecutionException, TimeoutException {
    return doGet(TimeUnit.MILLISECONDS.convert(timeout, unit));
  }

  private synchronized T doGet(Long timeoutMs)
      throws InterruptedException, ExecutionException, TimeoutException {
    if (mException != null) {
      throw new ExecutionException(mException);
    }

    if (mResultReceived) {
      return mResult;
    }

    if (isCancelled()) {
      throw new CancellationException();
    }

    if (timeoutMs == null) {
      wait(0);
    } else if (timeoutMs > 0) {
      wait(timeoutMs);
    }

    if (mException != null) {
      throw new ExecutionException(mException);
    }

    if (isCancelled()) {
      throw new CancellationException();
    }

    if (!mResultReceived) {
      throw new TimeoutException();
    }

    return mResult;
  }

  @Override
  public boolean isCancelled() {
    return mIsCancelled;
  }

  @Override
  public synchronized boolean isDone() {
    return mResultReceived || mException != null || isCancelled();
  }

  @Override
  public synchronized void onResponse(T response) {
    mResultReceived = true;
    mResult = response;
    notifyAll();
  }

  @Override
  public synchronized void onErrorResponse(VolleyError error) {
    mException = error;
    notifyAll();
  }
}

